Exploring regulated gene expression in complex biological systems often requires the ability to monitor expression of a large number of expressed genes in a simple, inexpensive assay. Nucleic acid hybridization on filter membranes (e.g., nitrocellulose or nylon) are familiar to most researchers practicing molecular biology, as is autoradiography, which has been the standard detection method for measuring gene expression via hybridization. True-color signals generated by chromogen-converting enzymes yield more information than just intensity, the focus of many known detection methods. Based on how the human eye works, true color can be separated into three components: hue, saturation, and brightness. Alternatively, true color can be separated into the subtractive primary colors cyan, magenta, and yellow. A slight change in any of the three components results in a difference often observable by the human eye.